Color filter on thin film transistor type liquid crystal display device and method of fabricating the same

ABSTRACT

A liquid crystal panel for a color filter on thin film transistor (COT) type liquid crystal display (LCD) device includes: first and second substrates facing each other and having a display area and a non-display area, the non-display area is at a periphery of the display area; a gate line and a data line on the first substrate, the gate line and the data line crossing each other to define a pixel region in the display area; a thin film transistor connected to the gate line and the data line; a color filter layer over the thin film transistor; a black matrix on the color filter layer; a pixel electrode contacting the thin film transistor on the color filer layer; a common electrode on the second substrate; a first alignment key on the second substrate in the non-display area; a sealant between the first and second substrates at a boundary between the display area and the non-display area; and a liquid crystal layer between the pixel electrode and the common electrode.

This application is a divisional application of U.S. patent applicationSer. No. 10/999,000, filed Nov. 30, 2004 now U.S. Pat. No. 7,612,860,which claims the benefit of Korean Patent Application No. 2003-0086271,filed on Dec. 1, 2003 and Korean Patent Application No. 2003-0086272,filed on Dec. 1, 2003, all of which are hereby incorporated by referencefor all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, and toa method of fabricating a liquid crystal display device, particularly acolor filter on thin film transistor (COT) type liquid crystal display(LCD) device and a method of fabricating the same.

2. Discussion of the Related Art

In general, liquid crystal display (LCD) devices make use of opticalanisotropy and polarization properties of liquid crystal molecules toproduce images. When an electric field is applied to liquid crystalmolecules, the liquid crystal molecules are rearranged. As a result, thetransmittance of the liquid crystal molecules is changed according tothe alignment direction of the rearranged liquid crystal molecules.

The LCD device includes two substrates disposed with their respectiveelectrodes facing each other, and a liquid crystal layer is interposedbetween the respective electrodes. When a voltage is applied to theelectrodes, an electric field is generated between the electrodes tomodulate the light transmittance of the liquid crystal layer byrearranging liquid crystal molecules, thereby displaying images.

FIG. 1 is an exploded perspective view of a liquid crystal display panelaccording to the related art. As shown in FIG. 1, a liquid crystal panel11 includes an upper substrate 5, a lower substrate 22 and a liquidcrystal material 14 interposed between the upper and lower substrates 5and 22. A black matrix 6 is formed on the upper substrate 5 and a colorfilter layer 8 including sub-color filters is formed on the black matrix6. A common electrode 18 is formed on the color filter layer 8. A pixelelectrode 17 and a thin film transistor (TFT) “T” used as a switchingelement are formed on the lower substrate 22 in a pixel region “P.” Thepixel electrode 17 is formed of a transparent conductive material, suchas indium-tin-oxide (ITO) and indium-zinc-oxide (IZO). The pixel region“P” is defined by a gate line 13 and a data line 15 and the TFT “T”disposed in matrix is connected to the gate line 13 and the data line15.

A storage capacitor “C” is connected in parallel to the pixel electrode17 and formed over the gate line 13. A portion of the gate line 13 isused as a first electrode of the storage capacitor “C”, and a metalpattern 30 with an island shape, which is in the same layer and is thesame material as the source and drain electrodes of the TFT “T,” is usedas a second electrode of the storage capacitor “C.” Because the metalpattern 30 is connected to the pixel electrode 17, the same signal isapplied to the metal pattern 30 and the pixel electrode 17.

The upper substrate 5 and the lower substrate 22 may be referred to as acolor filter substrate and an array substrate, respectively. Althoughnot shown in FIG. 1, the liquid crystal panel 11 may be embedded betweentop case and a bottom case to constitute a liquid crystal display (LCD)device.

FIG. 2 is a schematic cross-sectional view of an LCD device according tothe related art. In FIG. 2, a liquid crystal panel “D” includes a firstsubstrate 40, a second substrate 70 and liquid crystal (not shown)interposed between the first and second substrates 40 and 70. Apolarizing film 80 is formed on an outer surface of the second substrate70 and the liquid crystal panel “D” is fixed using a top case “TC.” Athin film transistor (TFT) “T” including a gate electrode 42, an activelayer 50, a source electrode 58 and a drain electrode 60 is formed onthe first substrate 40. In addition, a gate line 14 and a data line (notshown) crossing each other to define a pixel region “P” are formed onthe first substrate 40. A gate pad 46 is formed on one end of the gateline 14 and a gate pad terminal 66 of a transparent conductive materialis formed on the gate pad 46. Although not shown in FIG. 3, a data padis formed at one end of the data line with data pad terminal is formedon the data pad. The gate pad terminal 66 and the data pad terminal areconnected to an external circuit (not shown).

The first substrate 40 and the second substrate 70 are attached to eachother using a sealant 84. An alignment key “K” to attach the firstsubstrate 40 and the second substrate 70. An edge portion of the secondsubstrate 70 having the alignment key is cut out after attaching thefirst and second substrates 40 and 70 to expose the gate pad terminal 66and the data pad terminal in the edge portion on the second substrate70. A light-shielding pattern 74 is formed on a first portion of thesecond substrate 70 corresponding to the sealant 84. A black matrix 72is formed on a second portion of the second substrate 70 correspondingto the TFT “T,” the gate line 44 and the data line.

In general, a liquid crystal device includes a liquid crystal panel, abacklight unit, a top case and a bottom case. The top case is attachedto the bottom case with the liquid crystal panel and the backlight unitwithin the two cases. The liquid crystal panel has a display area and anon-display area at the periphery of the display area. The display areais exposed through the top case and the non-display area is covered bythe top case. However, the top case does not completely cover thenon-display area of the liquid crystal panel. Accordingly, an additionallight-shielding pattern is required in the non-display area of theliquid crystal panel.

The alignment key “K”, the light shielding pattern 74 and the blackmatrix 72 are simultaneously formed using a first mask process on thesecond substrate 70. A color filter layer 76 is formed on a thirdportion of the second substrate 70 corresponding to the pixel region “P”using a second mask process on the second substrate 70. A commonelectrode 78 is formed over the entire surface of the second substrate70 having the black matrix 72 and the color filter layer 76. Further, apatterned spacer 82 of a transparent organic material is formed on thecommon electrode 78 corresponding to the TFT “T” using a third maskprocess on the second substrate 70.

Because the liquid crystal panel “D” is obtained by attaching the lowersubstrate 40 having array elements such as the gate line 44, the dataline and the TFT “T and the second substrate 70 having the black matrix72 and the color filter layer 76, the liquid crystal panel “D” maydeteriorate due to a light leakage resulting from an alignment error. Inorder to overcome these problems, a color filter on TFT (COT) type hasbeen suggested where a color filter layer is formed on the firstsubstrate having a TFT.

FIG. 3 is a schematic cross-sectional view of a COT type LCD deviceaccording to the related art. In FIG. 3, a COT type liquid crystal panel100 includes a first substrate 110 and a second substrate 150 attachedto each other with a sealant 180. A TFT “T” having a gate electrode 112,an active layer 120, a source electrode 122 and a drain electrode 124 isformed on the first substrate 110. In addition, a gate line 114 and adata line (not shown) crossing each other to define a pixel region “P”are formed on the first substrate 110. A gate pad 116 is formed on oneend of the gate line 114 and a data pad (not shown) is formed at one endof the data line. A color filter layer 128 including red, green and bluesub-color filters (128 a, 128 b and not shown) and a black matrix 130are formed on the first substrate 110 having the TFT “T.” The colorfilter layer 128 corresponds to the pixel region “P” and the blackmatrix 130 corresponds to a channel region “CH” of the TFT “T.” Atransparent pixel electrode 134 contacting the drain electrode 124 isformed on the color filter layer 128 and a first orientation film 136 ofpolyimide is formed on the pixel electrode 134. A common electrode 152is formed on the second substrate 150 and a second orientation film 154is formed on the common electrode 152. In addition, a patterned spacer158 is formed on the second orientation film 154 corresponding to theTFT “T.”

In the COT type liquid crystal panel 100, the first and secondorientation films 136 and 154 are formed so as not to contact thesealant 180 because the polyimide for the orientation films has a poorcontact property with the sealant 180. When one of the first and secondorientation films 136 and 154 contact the sealant 180, the sealant 180may be broken. Accordingly, the first and second orientation films 136and 154 are spaced apart from the sealant 180 by a predetermineddistance “S1” as a fabrication margin. Since the predetermined distance“S1” causes an increase in the use of liquid crystal materials andfabrication costs, it is necessary to reduce the predetermined distance“S1.” In the COT type liquid crystal panel 100, the color filter layer128 and the black matrix 130 are formed on the first substrate 110 suchthat an additional deposition, photolithographic and etch steps arerequired to make an alignment key on the second substrate 150. Moreover,since the black matrix 130 is formed on the first substrate 110,additional deposition, photolithographic and etch steps are required toform a light-shielding pattern, which prevents leakage light at theboundary of the display area of the liquid crystal panel on the secondsubstrate 150. Thus, in the COT-type LCD device, additional steps arerequired to form an alignment key and a light-shielding pattern on asecond substrate, and these additional steps increase fabrication costsand fabrication time.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a color filter on thinfilm transistor (COT) type liquid crystal display (LCD) device and amethod of fabricating the same that substantially obviates one or moreof the problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a liquid crystaldisplay device and a method of fabricating a liquid crystal displaydevice having an improved production yield due to the reduced number offabrication processes.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. These andother advantages of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, a liquidcrystal panel for a color filter on thin film transistor (COT) typeliquid crystal display (LCD) device includes: first and secondsubstrates facing each other and having a display area and a non-displayarea, the non-display area is at a periphery of the display area; a gateline and a data line on the first substrate, the gate line and the dataline crossing each other to define a pixel region in the display area; athin film transistor connected to the gate line and the data line; acolor filter layer over the thin film transistor; a black matrix on thecolor filter layer; a pixel electrode contacting the thin filmtransistor on the color filer layer; a common electrode on the secondsubstrate; a first alignment key on the second substrate in thenon-display area; a sealant between the first and second substrates at aboundary between the display area and the non-display area; and a liquidcrystal layer between the pixel electrode and the common electrode.

In another aspect, a method of fabricating a liquid crystal panel for acolor filter on thin film transistor (COT) type liquid crystal display(LCD) device includes: forming a gate line and a data line on a firstsubstrate having a display area and a non-display area, the non-displayarea is at a periphery of the display area, the gate line and the dataline crossing each other to define a pixel region in the display area;forming a thin film transistor connected to the gate line and the dataline; forming a color filter layer over the thin film transistor;forming a black matrix on the color filter layer; forming a pixelelectrode contacting the thin film transistor on the color filter layer;forming a common electrode on a second substrate having the display areaand the non-display area; forming a first alignment key on the secondsubstrate in the non-display area; forming a sealant between the firstand second substrates at a boundary between the display area and thenon-display area; attaching the first and second substrates such thatthe pixel electrode faces the common electrode; and forming a liquidcrystal layer between the pixel electrode and the common electrode.

In another aspect, a color filter on thin film transistor (COT) typeliquid crystal display (LCD) device includes: first and secondsubstrates facing each other and having a display area and a non-displayarea, the non-display area is at a periphery of the display area; a gateline and a data line on the first substrate, the gate line and the dataline crossing each other to define a pixel region in the display area; athin film transistor connected to the gate line and the data line; acolor filter layer over the thin film transistor; a black matrix on thecolor filter layer; a pixel electrode contacting the thin filmtransistor on the color filer layer; a common electrode on the secondsubstrate; a light-shielding pattern at a boundary between the displayarea and the non-display area; a patterned spacer in the display area; asealant between the first and second substrates at the boundary betweenthe display area and the non-display area; a liquid crystal layerbetween the pixel electrode and the common electrode; and a top case anda bottom case enclosing the first and second substrates therein, whereinthe light-shielding pattern corresponds to end portions of the top case.

In another aspect, a method of fabricating a color filter on thin filmtransistor (COT) type liquid crystal display (LCD) device includes:forming a gate line and a data line on a first substrate having adisplay area and a non-display area, the non-display area is at aperiphery of the display area, the gate line and the data line crossingeach other to define a pixel region in the display area; forming a thinfilm transistor connected to the gate line and the data line; forming acolor filter layer over the thin film transistor; forming a black matrixon the color filter layer; forming a pixel electrode contacting the thinfilm transistor on the color filter layer; forming a common electrode ona second substrate having the display area and the non-display area;forming a first alignment key on the second substrate in the non-displayarea; forming a sealant between the first and second substrate at aboundary between the display area and the non-display area; attachingthe first and second substrates such that the pixel electrode faces thecommon electrode; forming a liquid crystal layer between the pixelelectrode and the common electrode; removing a portion of the secondsubstrate having the first alignment key; and forming a top case and abottom case enclosing the first and second substrates therein such thatthe light-shielding pattern corresponds to end portions of the top case.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is an exploded perspective view of a liquid crystal display panelaccording to the related art.

FIG. 2 is a schematic cross-sectional view of an LCD device according tothe related art.

FIG. 3 is a schematic cross-sectional view of a COT type LCD deviceaccording to the related art.

FIG. 4 is a schematic cross-sectional view of a COT type LCD deviceaccording to a first embodiment of the present invention.

FIG. 5 is a detailed cross-sectional view of a COT type LCD deviceaccording to a first embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a COT type LCD deviceaccording to a second embodiment of the present invention.

FIGS. 7A to 7C are schematic cross-sectional views showing a fabricationprocess of a second substrate for a COT type LCD device according to thesecond embodiment of the present invention.

FIG. 8 is a schematic plan view of a first substrate for a COT type LCDdevice according to the second embodiment of the present invention.

FIG. 9 is a schematic cross-sectional view, which is taken along a line“VII-VII” of FIG. 8, showing a first substrate for a COT type LCD deviceaccording to the second embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view, which is taken along a line“VIII-VIII” of FIG. 8, showing a first substrate for a COT type LCDdevice according to the second embodiment of the present invention.

FIG. 11 is a schematic cross-sectional view, which is taken along a line“IX-IX” of FIG. 8, showing a first substrate for a COT type LCD deviceaccording to the second embodiment of the present invention.

FIG. 12 is a schematic plan view showing a light-shielding pattern for aCOT type LCD device according to the second embodiment of the presentinvention.

FIG. 13 is a schematic cross-sectional view of a COT type LCD deviceaccording to a third embodiment of the present invention.

FIG. 14 is a schematic cross-sectional view showing a second substratefor a COT type LCD device according to a fourth embodiment of thepresent invention.

FIGS. 15A to 15B are schematic cross-sectional view showing afabrication process of a second substrate for a COT type LCD deviceaccording to the fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, similar reference numbers will be used torefer to the same or similar parts.

FIG. 4 is a schematic cross-sectional view of a COT type LCD deviceaccording to a first embodiment of the present invention. As shown inFIG. 4, a liquid crystal panel “LP” for a COT type LCD device includesfirst and second substrates 200 and 250 facing each other. Arrayelements “AP” including a color filter layer and a TFT are formed on thefirst substrate 200 and a first alignment key 202 is formed in aperipheral portion of the first substrate 200. The first alignment key202 may be formed of the same material and the same layer as the arrayelements AP. A common electrode 252 and an orientation film 254 aresequentially formed on the second substrate 250. In addition, a secondalignment key 256 is formed in a peripheral portion of the secondsubstrate 250. The orientation film 254 may be formed using a printingmethod or an inkjet method.

When the orientation film 254 is formed using a printing method, anorientation material, such as polyimide, is printed onto the secondsubstrate 250 using a printing plate having a predetermined patterncorresponding to the orientation film 254. An alignment key patterncorresponding to the second alignment key 256 may be further formed in aperipheral portion of the printing plate. Accordingly, the secondalignment key 256 is formed in the peripheral portion of the secondsubstrate 250 simultaneously with the orientation film 254. The secondalignment key 256 may be formed of a colorful resin, such as a resinhaving a pigment, instead of an orientation material. A colorful resinand an orientation material are coated on the printing plate, and thenthe colorful resin and the orientation material are printed onto thesecond substrate 250.

When the orientation film 254 is formed using an inkjet method, anorientation material is dropped onto the second substrate from an inkjethead. Since the movement of the inkjet head is easily controlled, theinkjet head may be programmed to form the second alignment key 256 inthe peripheral portion of the second substrate 250. Moreover, the secondalignment key 256 may be formed using a laser marking method. A lasermarking method melts a substrate with a laser beam to form the secondalignment key 256.

FIG. 5 is a detailed cross-sectional view of a COT type LCD deviceaccording to a first embodiment of the present invention. As shown inFIG. 5, a COT type LCD device includes a liquid crystal panel “LP” and atop case 390 surrounding the liquid crystal panel “LP.” The liquidcrystal panel “LP” includes first and second substrates 300 and 350having a display area “DA” used for displaying images and a non-displayarea “NDA” surrounding the display area “DA.” The display area “DA”includes a plurality of pixel regions “P” according to a size and aresolution of an LCD device. A gate line 304 and a data line (not shown)crossing each other to define the pixel region “P” are formed on thefirst substrate 300. A thin film transistor (TFT) “T” including a gateelectrode 302, an active layer 320, a source electrode 322 and a drainelectrode 324 is connected to the gate line 304 and the data line. Agate pad 306 is formed at one end of the gate line 304 and a data pad(not shown) is formed at one end of the data line. A passivation layer326 is formed on the TFT “T.” A color filter layer 328 including red,green and blue sub-color filters (328 a, 328 b and not shown) and ablack matrix 330 are formed on the first substrate 300 having the TFT“T.” The color filter layer 328 corresponds to the pixel region “P” andthe black matrix 330 corresponds to the TFT “T.” A planarization layer332 is formed on the color filter layer 328 and the black matrix 330. Atransparent pixel electrode 334 contacting the drain electrode 324 isformed on the planarization layer 332, and a first orientation film 336of polyimide is formed on the pixel electrode 334. A first alignment key308 may be formed of the same material and the same layer as a layerconstituting the TFT “T” in a peripheral portion of the first substrate300.

A common electrode 352 is formed on the second substrate 350 and asecond orientation film 354 is formed on the common electrode 352. Inaddition, a second alignment key 356 is formed in a peripheral portionof the second substrate 350. The second orientation film 354 may beformed using a printing method or an inkjet method.

When the second orientation film 354 is formed using a printing method,an orientation material, such as polyimide, is printed onto the secondsubstrate 350 using a printing plate having a predetermined patterncorresponding to the orientation film 354. An alignment key patterncorresponding to the second alignment key 356 may be further formed at aperipheral portion of the printing plate. Accordingly, the secondalignment key 356 is formed at the peripheral portion of the secondsubstrate 350 simultaneously with the orientation film 354. The secondalignment key 356 may be formed of a colorful resin, such as a resinhaving a pigment, instead of an orientation material. A colorful resinand an orientation material are coated on the printing plate, and thenthe colorful resin and the orientation material are printed onto thesecond substrate 350. When the orientation film 354 is formed using aninkjet method, an orientation material is dropped onto the secondsubstrate from an inkjet head. Since the movement of the inkjet head iseasily controlled, the inkjet head may be programmed to form the secondalignment key 356 at the peripheral portion of the second substrate 350.Moreover, the second alignment key 356 may be formed using a lasermarking method. A laser marking method melts a substrate with a laserbeam to form the second alignment key 356.

The first and second substrates 300 and 350 are aligned with each otherusing the first and second alignment keys 308 and 356. A charge-coupleddevice (CCD) camera may be used for aligning the first and secondalignment keys 308 and 356. Accordingly, a predetermined distance from asealant 380 to the orientation films 336 and 354 is minimized and thusreducing fabrication costs. After attaching the first and secondsubstrates 300 and 350, portions of the first and second substrates 300and 350 having the first and second alignment keys 308 and 356 are cutaway to expose the gate pad 306 and the data pad.

A fabrication process of the first substrate 300 is illustratedhereinafter. After forming the gate line 304 and the gate electrode 302on the first substrate 300, a gate insulating layer “GI” is formed onthe gate line 304 and the gate electrode 302. Next, the active layer 320and the ohmic contact layer “OC” are formed on the gate insulating layer“GI” corresponding to the gate electrode 302. The active layer 320 mayinclude intrinsic amorphous silicon (a-Si:H) and the ohmic contact layer“OC” may include impurity-doped amorphous silicon (n+ a-Si:H or p+a-Si:H). Next, the source and drain electrodes 322 and 324 spaced apartfrom each other are formed on the ohmic contact layer “OC” and the dataline (not shown) contacting the source electrode 322 is formed on thegate insulating layer “GI.” Next, a passivation layer is formed on thesource and drain electrodes 322 and 324. The passivation layer mayinclude one of an inorganic insulating material, such as silicon nitride(SiNx) and silicon oxide (SiO₂). Next, the color filter layer 328 andthe black matrix 330 are formed on the passivation layer. Aplanarization layer 332 is then formed on the color filter layer 328 andthe black matrix 330. The planarization layer 332 may include an organicinsulating material, such as benzocyclobutene (BCB) and acrylic resin.Next, after the pixel electrode 334 is formed on the planarization layer332, the first orientation film 336 is formed on the pixel electrode334. However, since the top case 390 may not completely shield a lightleakage through a portion adjacent to the sealant 380, a light-shieldingpattern is required.

FIG. 6 is a schematic cross-sectional view of a COT type LCD deviceaccording to a second embodiment of the present invention. As shown inFIG. 6, a COT type LCD device 498 includes a liquid crystal panel “LP”and a top case 480 surrounding the liquid crystal panel “LP.” The liquidcrystal panel “LP” includes first and second substrates 400 and 450attached with a sealant 460, and a polarization film 470 is formed on anouter surface of the second substrate 450. The liquid crystal panel “LP”has a display area “DA” used for displaying images and a non-displayarea “NDA” surrounding the display area “DA.” The display area “DA”includes a plurality of pixel regions “P” according to a size and aresolution of an LCD device.

A gate line 404 and a data line (not shown) crossing each other todefine the pixel region “P” are formed on the first substrate 400. Athin film transistor (TFT) “T” including a gate electrode 402, an activelayer 410, a source electrode 412 and a drain electrode 414 is connectedto the gate line 404 and the data line. A gate pad 406 is formed at oneend of the gate line 404 and a data pad (not shown) is formed at one endof the data line. A passivation layer 416 is formed on the TFT “T.” Acolor filter layer 418 including red, green and blue sub-color filters(418 a, 418 b and not shown) and a black matrix 420 are formed on thefirst substrate 400 having the TFT “T.” The color filter layer 418corresponds to the pixel region “P” and the black matrix 420 correspondsto the TFT “T.” A planarization layer 422 is formed on the color filterlayer 418 and the black matrix 420. A transparent pixel electrode 424contacting the drain electrode 414 is formed on the planarization layer422. Even though not shown in FIG. 6, a first orientation film ofpolyimide may be formed on the pixel electrode 424, and a firstalignment key may be formed of the same material and in the same layeras a layer constituting the TFT “T” in a peripheral portion of the firstsubstrate 400.

A common electrode “CL” is formed on the second substrate 450. Inaddition, a second alignment key 452, a light-shielding pattern 454 anda patterned spacer 456 are formed on the common electrode “CL.” Thesecond alignment key 452 may be formed in a peripheral portion of thesecond substrate 450 corresponding to the first alignment key (notshown). The light-shielding pattern 454 may be formed to correspond to aperiphery of the top case 480, and the patterned spacer 456 may beformed to correspond to the TFT “T.” Each of the second alignment key452, the light-shielding pattern 454 and the patterned spacer 456 mayhave a first sub-layer 452 a, 454 a and 456 a and a second sub-layer 452b, 454 b and 456 b formed using a single mask process.

FIGS. 7A to 7C are schematic cross-sectional views showing a fabricationprocess of a second substrate for a COT type LCD device according to asecond embodiment of the present invention.

In FIG. 7A, a common electrode “CL” is formed on a second substrate 450having a display are “DA” and a non-display area “NDA” by depositing oneof indium-tin-oxide (ITO) and indium-zinc-oxide (IZO). An opaquematerial layer “M” is formed on the common electrode “CL” and an organicmaterial layer “O” is formed on the opaque material layer “M.” Theopaque material layer “M” may include an opaque material shielding lightsuch as chromium oxide (CrOx), and the organic material layer “O” mayinclude a photosensitive transparent organic material. In addition, thephotosensitive transparent organic material may have a positive type ora negative type. For illustration, a positive type organic material isused in FIGS. 7A to 7C. Further, the non-display area “NDA” may includean alignment key area “AK” and a light-shielding pattern area “LSPA”where a second alignment key and a light-shielding pattern are formed ina subsequent process, respectively. The light-shielding pattern area“LSPA” is defined to surround the display area “DA.” After forming theorganic material layer “O,” a mask 490 having a transmissive portion“TP” and a blocking portion “BP” is disposed over the organic materiallayer “O.” Next, the organic material layer “O” is exposed to lightthrough the mask 490 and then the exposed organic material layer “O” isdeveloped.

In FIG. 7B, first, second and third organic material patterns 452 b, 454b and 456 b corresponding to the blocking portion “BP” of the mask 490are formed on the opaque material layer “M.” The first and secondorganic material patterns 452 b and 454 b are formed in the alignmentkey area “AK” and the light-shielding pattern area “LSPA,” respectively.In addition, the third organic material pattern 456 b is formed in thedisplay area “DA” and functions as a spacer for maintaining a uniformcell gap of a liquid crystal panel. Next, the opaque material layer “M”is patterned using the first, second and third organic material patterns452 b, 454 b and 456 b as an etch mask.

In FIG. 7C, first, second and third opaque material patterns 452 a, 454a and 456 a are formed on the common electrode “CL.” Accordingly, asecond alignment key 452 having the first opaque material pattern 452 aand the first organic material pattern 452 b is formed in the alignmentkey area “AK” and a light-shielding pattern 454 having the second opaquematerial pattern 454 a and the second organic material pattern 454 b isformed in the light-shielding pattern area “LSPA.” In addition, apatterned spacer 456 having the third opaque material pattern 456 a andthe third organic material pattern 456 b is formed in the display area“DA.” The patterned spacer 456 may be disposed at a random position ofthe display area “DA.” As a result, the second alignment key 452, thelight-shielding pattern 454 and the patterned spacer 456 are formed overthe second substrate 450 using a single mask process.

FIG. 8 is a schematic plan view of a first substrate for a COT type LCDdevice according to a second embodiment of the present invention. Asshown in FIG. 8, a gate line 404 and a data line “DL” crossing eachother to define a pixel region “P” are formed on a first substrate 400having a display area “DA” and a non-display area “NDA.” A gate pad 406is formed at one end of the gate line 404 and a data pad “DP” is formedat one end of the data line “DL.” A thin film transistor (TFT) “T”including a gate electrode 402, an active layer 410, a source electrode412 and a drain electrode 414 are connected to the gate line 404 and thedata line “DL.” A color filter layer 418 including red, green and bluesub-color filters 418 a, 418 b and 418 c is formed in the pixel region“P” and a black matrix (not shown) is formed to correspond to the TFT“T.” A transparent pixel electrode 424 contacting the drain electrode414 is formed on the color filter layer 418. In addition, a capacitorelectrode “CM” having an island shape may be formed to overlap a portionof the gate line 404. The capacitor electrode “CM” may be connected tothe pixel electrode 424, thereby the capacitor electrode “CM” and theoverlapping portion of the gate line 404 constituting a storagecapacitor “C_(ST).”

FIGS. 9, 10 and 11 are schematic cross-sectional views showing a firstsubstrate for a COT type LCD device according to a second embodiment ofthe present invention. FIG. 9 is taken along a line “VII-VII” of FIG. 8,FIG. 10 is taken along a line “VIII-VIII” of FIG. 8, and FIG. 11 istaken along a line “IX-IX” of FIG. 8.

As shown in FIGS. 9, 10 and 11, a gate line 404, a gate pad 406 and agate electrode 402 are formed on a first substrate 400. The gate pad 406and gate electrode 402 are connected to the gate line 404. A gateinsulating layer 408 is formed on the gate line 404, the gate pad 406and the gate electrode 402. The gate insulating layer 408 may include aninorganic insulating materials, such as silicon nitride (SiNx) andsilicon oxide (SiO₂). An active layer 410 and an ohmic contact layer“OCL” having an island shape are sequentially formed on the gateinsulating layer 408 corresponding to the gate electrode 402. Source anddrain electrodes 412 and 414 spaced from each other are formed on theohmic contact layer “OCL.” A data line “DL” (of FIG. 8) and a data pad“DP” connected to the data line “DL” (of FIG. 8) are simultaneouslyformed with the source and drain electrode 412 and 414. The data line“DL” (of FIG. 8) is connected to the source electrode 412 and crossesthe gate line 404 to define a pixel region “P.” The source electrode412, the drain electrode 414, the data line “DL” (of FIG. 8) and thedata pad “DP” may include a conductive metallic material. The gateelectrode 402, the active layer 210, the ohmic contact layer “OCL,” thesource electrode 412 and the drain electrode 414 constitute a thin filmtransistor (TFT) “T.” A passivation layer 416 of an inorganic insulatingmaterial is formed on the TFT “T.”

A black matrix 420 is formed on the passivation layer 416 to correspondto the TFT “T,” the gate line 404 and the data line “DL” (of FIG. 8).The black matrix 420 over the gate line 404 and the data line “DL” (ofFIG. 8) may be omitted in a high aperture ratio structure LCD device. Acolor filter layer 418 including red, green and blue sub-color filters418 a, 418 b and 418 c (of FIG. 8) is formed in the pixel region “P.” Inaddition, a planarization layer 422 of a transparent organic material isformed on the black matrix 420 and the color filter layer 418. Atransparent pixel electrode 424 contacting the drain electrode 414 isformed on the planarization layer 422.

The first substrate 400 of FIGS. 8, 9, 10 and 11 and the secondsubstrate 450 of FIGS. 7A to 7C are attached with the sealant 460 (ofFIG. 6) to constitute a liquid crystal panel “LP” (of FIG. 6). Thesealant 460 (of FIG. 6) is formed between the gate line 404 (of FIG. 6)and the gate pad 406 (of FIG. 6) and between the data line “DL” (of FIG.8) and the data pad “DP” (of FIG. 8). The first and second substrates400 and 450 (of FIG. 6) are aligned with each other using the firstalignment key (not shown) and the second alignment key 452 (of FIG. 6).For example, the first and second substrates 400 and 450 (of FIG. 6) maybe put together in an incomplete alignment state and then the alignmentstate of the first and second substrates 400 and 450 (of FIG. 6) may beminutely adjusted using the first alignment key (not shown) and thesecond alignment key 452 (of FIG. 6). Then, the first and secondsubstrates 400 and 450 (of FIG. 6) may be attached in a completealignment state. After attaching the first and second substrates 400 and450 (of FIG. 6), portions of the first and second substrates 400 and 450(of FIG. 6) having the first alignment key (not shown) and the secondalignment key 452 (of FIG. 6) may be cut away to expose the gate pad 406(of FIG. 6) and the data pad “DP” (of FIG. 8).

When the first and second substrates 400 and 450 (of FIG. 6) move toadjust the alignment state thereof minutely, the second organic materialpattern 454 b of the light-shielding pattern 454 may contact a toplayer, for example, the planarization layer 422 (of FIG. 6) of the firstsubstrate 400. As a result, it is difficult to move the first and secondsubstrates 400 and 450 (of FIG. 6) due to a friction between the secondorganic material pattern 454 b and the top layer. To solve theseproblems, an exemplary structure of the light-shielding pattern 454 isillustrated hereinafter.

FIG. 12 is a schematic plan view showing a light-shielding pattern for aCOT type LCD device according to a second embodiment of the presentinvention. As shown in FIG. 12, a plurality of gate lines 404 are formedon a second substrate (not shown). A light-shielding pattern 454 isformed between adjacent gate lines 404 to reduce a contact area of thelight-shielding pattern 454 and the top layer (not shown). Since thegate lines 404 also shield light, light may be completely shielded inFIG. 10.

FIG. 13 is a schematic cross-sectional view of a COT type LCD deviceaccording to a third embodiment of the present invention. As shown inFIG. 13, a COT type LCD device 598 includes a liquid crystal panel “LP”and a top case 580 surrounding the liquid crystal panel “LP.” The liquidcrystal panel “LP” includes first and second substrates 500 and 550attached with a sealant 560, and a polarization film 570 is formed on anouter surface of the second substrate 550. The liquid crystal panel “LP”has a display area “DA” used for displaying images and a non-displayarea “NDA” surrounding the display area “DA.” The display area “DA”includes a plurality of pixel regions “P” according to a size and aresolution of an LCD device.

A gate line 504 and a data line (not shown) crossing each other todefine the pixel region “P” are formed on the first substrate 500. Athin film transistor (TFT) “T” including a gate electrode 502, an activelayer 510, a source electrode 512 and a drain electrode 514 is connectedto the gate line 404 and the data line. A gate pad 506 is formed at oneend of the gate line 504 and a data pad (not shown) is formed at one endof the data line. A passivation layer 516 is formed on the TFT “T.” Acolor filter layer 518 including red, green and blue sub-color filters(518 a, 518 b and not shown) and a black matrix 520 are formed on thefirst substrate 500 having the TFT “T.” The color filter layer 518corresponds to the pixel region “P” and the black matrix 520 correspondsto the TFT “T.” A planarization layer 522 is formed on the color filterlayer 518 and the black matrix 520. A transparent pixel electrode 524contacting the drain electrode 514 is formed on the planarization layer522. Although not shown in FIG. 13, a first orientation film ofpolyimide may be formed on the pixel electrode 524, and a firstalignment key may be formed of the same material and in the same layeras a layer constituting the TFT “T” in a peripheral portion of the firstsubstrate 500.

A common electrode “CL” is formed on the second substrate 550. Inaddition, a second alignment key 552, a light-shielding pattern 554 anda patterned spacer 556 are formed on the common electrode “CL.” Thesecond alignment key 552 may be formed in a peripheral portion of thesecond substrate 550 corresponding to the first alignment key (notshown) of the first substrate 500. The light-shielding pattern 554 maybe formed to correspond to a periphery of the top case 580 and thesealant 560. In addition or in the alternative, the patterned spacer 556may be formed to correspond to the TFT “T.” Each of the second alignmentkey 552, the light-shielding pattern 554 and the patterned spacer 556may have a first sub-layer 552 a, 554 a and 556 a and a second sub-layer552 b, 554 b and 556 b formed using a single mask process. The firstsub-layer 552 a, 554 a and 556 a may include an opaque metallic materialand the second sub-layer 552 b, 554 b and 556 b may include atransparent organic material.

Since the light-shielding pattern 554 extends beyond the sealant 560 andthe sealant 560 is formed on the light-shielding pattern 554, a marginfor the top case 580 is improved and a height of the sealant 560 isreduced. In addition, even though not shown in FIG. 13, thelight-shielding pattern 554 may be formed between adjacent gate lines504 and between adjacent data lines to reduce a contact area of thelight-shielding pattern 554 and a top layer of the first substrate 500.Since the gate lines 504 and the data lines also shield light, light maybe completely shielded in a peripheral portion of the liquid crystalpanel “LP.”

FIG. 14 is a schematic cross-sectional view showing a second substratefor a COT type LCD device according to a fourth embodiment of thepresent invention. As shown in FIG. 14, a common electrode “CL” isformed on a second substrate 650 having a display area “DA” used fordisplaying images and a non-display area “NDA” surrounding the displayarea “DA.” A second alignment key 652, a light-shielding pattern 654 anda patterned spacer 656 are formed on the common electrode “CL.” Thesecond alignment key 652 and the light-shielding pattern 654 are formedin the non-display area “DA” and the patterned spacer 656 is formed inthe display area “DA.” Each of the second alignment key 652, thelight-shielding pattern 654 and the patterned spacer 656 may have afirst sub-layer 652 a, 554 a and 656 a and a second sub-layer 652 b, 654b and 656 b formed using a single mask process. The first sub-layer 652a, 654 a and 656 a may include an opaque material and the secondsub-layer 652 b, 654 b and 656 b may include a transparent organicmaterial.

The second alignment key 652, the light-shielding pattern 654 and thepatterned spacer 656 is formed using a mask having a half-transmissiveportion. Accordingly, the patterned spacer 656 may have a height greaterthan the light-shielding pattern 654 because the second sub-layer 656 bof the patterned spacer 656 is thicker than the second sub-layer 654 bof the light-shielding pattern 654. As a result, the light-shieldingpattern 654 may not contact a top layer of the first substrate even whenthe first and second substrates for the liquid crystal panel move toadjust the alignment state thereof minutely. Therefore, an alignmenterror due to friction between the second sub-layer 654 b oflight-shielding pattern 654 and the top layer of the first substrate isprevented.

FIGS. 15A to 15B are schematic cross-sectional view showing afabrication process of a second substrate for a COT type LCD deviceaccording to a fourth embodiment of the present invention. As shown inFIG. 15A, a common electrode “CL” is formed on a second substrate 650having a display area “DA” used for displaying images and a non-displayarea “NDA” surrounding the display area “DA.” The common electrode “CL”may include one of transparent conductive materials, such asindium-tin-oxide (ITO) and indium-zinc-oxide (IZO). Next, an opaquematerial layer “M” and an organic material layer “O” are sequentiallyformed on the common electrode “CL.” The opaque material layer “M” mayinclude an opaque material shielding light such as chromium oxide(CrOx), and the organic material layer “O” may include a photosensitivetransparent organic material. In addition, the photosensitivetransparent organic material may have a positive type or a negativetype. For illustration, a positive type organic material is used inFIGS. 15A to 15C.

The non-display area “NDA” may include an alignment key area “AK” and alight-shielding pattern area “LSPA” where a second alignment key and alight-shielding pattern are formed in a subsequent process,respectively. The light-shielding pattern area “LSPA” is defined tosurround the display area “DA.” After forming the organic material layer“O,” a mask 690 having a transmissive portion “TP,” a half-transmissiveportion “HTP” corresponding to the light shielding pattern area “LSPA,”and a blocking portion “BP” is disposed over the organic material layer“O.” The half-transmissive portion “HTP” has a light transmittance lowerthan the transmissive portion “TP” and higher than the blocking portion“BP.” In addition, the half-transmissive portion “HTP” may be formed ofa half-tone film or a slit. Next, the organic material layer “O” isexposed to a light through the mask 690 and then the exposed organicmaterial layer “O” is developed.

In FIG. 15B, first, second and third organic material patterns 652 b,654 b and 656 b are formed on the opaque material layer “M.” The secondorganic material pattern 654 b and the third organic material pattern656 b correspond to the half-transmissive portion “HTP” and the blockingportion “BP” of the mask 690 (of FIG. 15A), respectively. Even thoughthe blocking portion “BP” correspond to the first organic pattern 652 bin FIG. 15A, the half-transmissive portion “HTP” may correspond to thefirst organic pattern 652 b in another embodiment. Accordingly, thesecond organic material pattern 654 b has a height lower than the thirdorganic material pattern 656 b. The first and second organic materialpatterns 652 b and 654 b are formed in the alignment key area “AK” andthe light-shielding pattern area “LSPA,” respectively. In addition, thethird organic material pattern 656 b is formed in the display area “DA”and functions as a spacer for maintaining a uniform cell gap of a liquidcrystal panel. Next, the opaque material layer “M” is patterned usingthe first, second and third organic material patterns 652 b, 654 b and656 b as an etch mask.

In FIG. 15C, first, second and third opaque material patterns 652 a, 654a and 656 a are formed on the common electrode “CL.” Accordingly, asecond alignment key 652 having the first opaque material pattern 652 aand the first organic material pattern 652 b is formed in the alignmentkey area “AK” and a light-shielding pattern 654 having the second opaquematerial pattern 654 a and the second organic material pattern 654 b isformed in the light-shielding pattern area “LSPA.” In addition, apatterned spacer 656 having the third opaque material pattern 656 a andthe third organic material pattern 656 b is formed in the display area“DA.” The patterned spacer 656 may be disposed at a random position ofthe display area “DA.” As a result, the second alignment key 652, thelight-shielding pattern 654 and the patterned spacer 656 having a heighthigher than the light-shielding pattern 654 are formed over the secondsubstrate 650 using a single mask process.

In a COT type LCD device according to the present invention, since adistance between a sealant and an orientation film is minimized, dummyspace is decreased and a fabrication costs are reduced. In addition,since an alignment key, a light-shielding pattern and a patterned spacerare formed using a single mask process, a fabrication process issimplified and production yield is improved. Moreover, since alight-shielding pattern is formed between adjacent gate lines andadjacent data lines, contact area between a top layer of a firstsubstrate and an organic material layer of a second substrate isreduced, thereby an alignment error due to friction is prevented.Furthermore, a sufficient fabrication margin for a top case is obtainedby extending a light-shielding pattern to a sealant. Thus, alight-shielding pattern is formed to have a height lower than apatterned spacer using a mask having a half-transmissive portion.Accordingly, a contact area between a top layer of a first substrate andan organic material layer of a second substrate is further reduced,thereby preventing an alignment error due to friction.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method of fabricating a liquid crystal panel for a color filter onthin film transistor (COT) type liquid crystal display (LCD) device,comprising: forming a gate line and a data line on a first substratehaving a display area and a non-display area, the non-display area is ata periphery of the display area, the gate line and the data linecrossing each other to define a pixel region in the display area;forming a thin film transistor connected to the gate line and the dataline; forming a color filter layer over the thin film transistor;forming a black matrix on the color filter layer; forming a pixelelectrode contacting the thin film transistor on the color filter layer;forming a common electrode on a second substrate having the display areaand the non-display area; forming a first alignment key on the secondsubstrate in the non-display area; forming a first orientation film onthe common electrode; forming a sealant between the first and secondsubstrates at a boundary between the display area and the non-displayarea; attaching the first and second substrates such that the pixelelectrode faces the common electrode; and forming a liquid crystal layerbetween the pixel electrode and the common electrode, wherein the firstalignment key is simultaneously formed with the first orientation film.2. The method according to claim 1, further comprising forming a secondorientation film on the pixel electrode.
 3. The method according toclaim 2, wherein the first alignment key is formed using one of aprinting method and an inkjet method.
 4. The method according to claim1, wherein the first alignment key is formed by partially melting asurface of the second substrate in the non-display area.
 5. The methodaccording to claim 1, further comprising forming a second alignment keyon the first substrate corresponding to the first alignment key.
 6. Themethod according to claim 5, wherein the second alignment key issimultaneously formed with the gate line and the data line.
 7. Themethod according to claim 1, further comprising forming alight-shielding pattern at the boundary between the display area and thenon-display area; and forming a patterned spacer in the display areawhile simultaneously forming the first alignment key.
 8. The methodaccording to claim 7, wherein the forming the first alignment key, thelight-shielding pattern and the patterned spacer includes: forming anopaque material layer on the second substrate having the commonelectrode; forming a photosensitive organic material layer on the opaquematerial layer; exposing the photosensitive organic material layerthrough a mask having a transmissive portion and a blocking portion;developing the photosensitive organic material layer to form first,second and third organic material patterns; and patterning the opaquematerial layer using the first, second and third organic materialpatterns to form first, second and third opaque material patterns asetch masks, wherein the first opaque material pattern and the firstorganic material pattern constitute the first alignment key, the secondopaque material pattern and the second organic material patternconstitute the light-shielding pattern, and the third opaque materialpattern and the third organic material pattern constitute the patternedspacer.
 9. The method according to claim 7, wherein the forming thefirst alignment key, the light-shielding pattern and the patternedspacer includes: forming an opaque material layer on the secondsubstrate having the common electrode; forming a photosensitive organicmaterial layer on the opaque material layer; exposing the photosensitiveorganic material layer through a mask having a transmissive portion, ahalf-transmissive portion and a blocking portion; developing thephotosensitive organic material layer to form first, second and thirdorganic material patterns, the second and third organic materialpatterns corresponding to the half-transmissive portion and the blockingportion, respectively; and patterning the opaque material layer usingthe first, second and third organic material patterns to form first,second and third opaque material patterns as etch masks, wherein thefirst opaque material pattern and the first organic material patternconstitute the first alignment key, the second opaque material patternand the second organic material pattern constitute the light-shieldingpattern, and the third opaque material pattern and the third organicmaterial pattern constitute the patterned spacer.
 10. The methodaccording to claim 7, wherein the light-shielding pattern overlaps thesealant.
 11. The method according to claim 7, wherein thelight-shielding pattern is formed between the adjacent gate lines andbetween the adjacent data lines.
 12. A method of fabricating a colorfilter on thin film transistor (COT) type liquid crystal display (LCD)device, comprising: forming a gate line and a data line on a firstsubstrate having a display area and a non-display area, the non-displayarea is at a periphery of the display area, the gate line and the dataline crossing each other to define a pixel region in the display area;forming a thin film transistor connected to the gate line and the dataline; forming a color filter layer over the thin film transistor;forming a black matrix on the color filter layer; forming a pixelelectrode contacting the thin film transistor on the color filter layer;forming a common electrode on a second substrate having the display areaand the non-display area; forming a first alignment key on the secondsubstrate in the non-display area; forming a light-shielding pattern ata boundary and a patterned spacer in the display area; forming a sealantbetween the first and second substrate at the boundary between thedisplay area and the non-display area; attaching the first and secondsubstrates such that the pixel electrode faces the common electrode;forming a liquid crystal layer between the pixel electrode and thecommon electrode; removing a portion of the second substrate having thefirst alignment key; and forming a top case and a bottom case enclosingthe first and second substrates therein such that the light-shieldingpattern corresponds to end portions of the top case, wherein thelight-shielding pattern and the patterned spacer are simultaneouslyformed with the first alignment key.
 13. The method according to claim12, wherein forming the first alignment key, the light-shielding patternand the patterned spacer includes: forming an opaque material layer onthe second substrate having the common electrode; forming aphotosensitive organic material layer on the opaque material layer;exposing the photosensitive organic material layer through a mask havinga transmissive portion and a blocking portion; developing thephotosensitive organic material layer to form first, second and thirdorganic material patterns; and patterning the opaque material layerusing the first, second and third organic material patterns to formfirst, second and third opaque material patterns as etch masks, whereinthe first opaque material pattern and the first organic material patternconstitute the first alignment key, the second opaque material patternand the second organic material pattern constitute the light-shieldingpattern, and the third opaque material pattern and the third organicmaterial pattern constitute the patterned spacer.
 14. The methodaccording to claim 12, wherein the forming the first alignment key, thelight-shielding pattern and the patterned spacer includes: forming anopaque material layer on the second substrate having the commonelectrode; forming a photosensitive organic material layer on the opaquematerial layer; exposing the photosensitive organic material layerthrough a mask having a transmissive portion, a half-transmissiveportion and a blocking portion; developing the photosensitive organicmaterial layer to form first, second and third organic materialpatterns, the second and third organic material patterns correspondingto the half-transmissive portion and the blocking portion, respectively;and patterning the opaque material layer using the first, second andthird organic material patterns to form first, second and third opaquematerial patterns as etch masks, wherein the first opaque materialpattern and the first organic material pattern constitute the firstalignment key, the second opaque material pattern and the second organicmaterial pattern constitute the light-shielding pattern, and the thirdopaque material pattern and the third organic material patternconstitute the patterned spacer.